Graphite Pressure Seals

Graphite Pressure Seal

In pressure seal valves, sealing is provided by the wedge shaped metal pressure seal gasket, which uses the pressure load on the valve bonnet to develop metal to metal contact between both the gasket/body and gasket/bonnet. Both the metal gasket and the bonnet are retained in the valve by a fixed retainer.

The replacement of a pressure seal ring can become one of the most frustrating maintenance jobs around. The success ratio seems to decline with the age of the valve and can be attributed to the valve condition. With age, valves can experience some in-service fatigue. The valve has to withstand system operation, elongation pipe stress, thermal fluctuation, mild corrosion, perhaps abrasion, even radiation and the wear and tear associated with disassembly.

Metal pressure seals typically encounter the following issues:
  • Extremely precise fit required for leak-free service
  • As the valve ages, normal corrosion, wear, and galling that deteriorates the body or bonnet surfaces can impact sealing
  • Disassembly can be very difficult; as the parts are actually wedged together, contact forces can be so high that the silver plating on the gasket transfers on to the body
  • High price and long lead time

Unlike metal pressure seals, AP Services' graphite pressure seals are very forgiving to valve abnormalities due to the ability of the graphite to flow and fill imperfections. Graphite pressure seals are often significantly cheaper than metal pressure seals and can often be delivered next day. With over 25 years of experience manufacturing graphite pressure seals to OEMs and the Power Gen markets, we offer the best commercial and Nuclear Grade graphite seals for your pressure seal valves.

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